This invention is concerned with a remote control system and more particularly with a transmitting unit distant and separate from a receiver unit, the latter being carried by a device; e.g. a toy vehicle for control thereof by the transmitting unit. The invention also relates to a method in which a single transmitting frequency serves under specified conditions to control diverse movements of the movable device.
It is known from U.S. Pat. No. 3,720,281 to use high frequency carrier signals to control the movement of the rear wheels of a golf club carrier or golf cart. In the disclosed device, movement of the vehicle is under control of separate drive motors for the rear wheels as a function of signals received by a pair of antennae. The need for left and right antennae for this purpose complicates the system making it more costly and more likely to malfunction due to its increased complexity.
It is also known to control machinery from a remote location, as exemplified by the disclosure of U.S. Pat. No. 3,454,927. In particular, a transmitter is provided which generates a fixed sequence of tone groups, one of which is a low frequency tone and the other of which is a high frequency tone. One tone is for function control while the other determines the operation to be carried out by the function selected. The tones of the different frequencies are separated at the receiver unit. To discriminate between tones of different frequencies, a multiple channel receiver must be used which again adds to the complexity and cost of the device, both undesirable factors since toys to be marketable must be of simple design and low cost construction.